1. Field of the Invention
The present invention relates to a system for processing and reproducing multichannel audio signals.
2. Related Art
With recent years, video software such as movies have included multichannel audio signals recorded therein in accordance with a system such as the Dolby Digital (trademark) or the DTS (Digital Theater System) (trademark), in order to enable an audio reproduction with an enhanced ambience and a powerful sound. In case where the video software is reproduced, image signals are generally reproduced by means of a video monitor, while reproducing multichannel audio signals utilizing amplifiers and loudspeakers for two to eight channels. There are many cases where such multichannel audio signals have a central channel audio signal in which signal components for a human voice such as spoken words contained in video contents such as a video movie, or vocalized lyrics contained in musical contents are included.
In general, when reproducing the above-mentioned multichannel audio signals, a pair of front loudspeakers (for the R-channel and the L-channel) is often disposed on the right and left-hand sides of a video monitor, which is placed in front of an audience, and a central loudspeaker is often disposed above or below the video monitor. In such a case, reproducing the audio signal of the central channel, which is included in the multichannel audio signals, through the central loudspeaker, without subjecting such an audio signal to any processing, causes an audio image for the central channel to be drawn not to a position of the video monitor, but to the central loudspeaker. This may cause an audience to feel that spoken words and/or vocalized lyrics contained in the video contents are heard not from an image such as a person displayed on the video monitor, but from the position located above or below the video monitor, resulting in an uncomfortable feeling.
Japanese Laid-Open Patent Application No. H9-37384 (hereinafter referred to as the “Prior Art 1”) discloses one of the methods of solving the above-described problem. According to the method of the Prior Art 1, the audio signals of the central channel, from which signal components having the predetermined frequency band have been removed, are reproduced, thus making it difficult for an audience to recognize the position of a sound source. This utilizes the auditory psychological property that an audience senses as if a sound source exists in his/her viewing direction, when an audio image is too unclear for him/her to recognize the position of the sound source, to cause him/her to feel that spoken words and/or vocalized lyrics based on the audio signals of the central channel come from the center of the video monitor.
The above-described method, which utilizes an auditory illusion of a human being, does not always cause everyone to feel that spoken words and/or vocalized lyrics based on the audio signals of the central channel come from the center of the video monitor. Utilizing the auditory psychological property to make forcedly it difficult for an audience to recognize the position of a sound source may cause him/her to have an uncomfortable feeling accordingly.